Torsion bar sheet separator



0a. 1, 1968 J. w. cm. 3,403,903

TORSION BAR SHEET SEPARATOR Filed April 1'7, 1967 United States Patent"ice 3,403,903 TORSION BAR SHEET SEPARATOR Jesse W. Crail, 3802Edenhurst Ave., Los Angeles, Calif. 90039 Filed Apr. 17, 1967, Ser. No.631,272 4 Claims. (Cl. 271-20) I ABSTRACT OF THE DISCLOSURE A vacuumlifter removes the top sheet from a stack which has a vertical stopplate at the forward side of the stack adjacent the upper leading edge.Separator finger means are mounted on a tubular shaft which hasassociated therewith torsion bar structure for exerting a force on theseparator fingers while the lifter means is removing a top sheet.

The present invention relates generally to mechanical finger devices forseparating sheets of paper as they are fed by vacuum lifter means into amultilith machine or the like. More particularly, the invention relatesto a sheet separator for use in a vacuum lifter paper feed system, inwhich one or several rigid separator fingers are resiliently moveable onenclosed torsion bar spring systems.

This invention was specially invented to meet a need in multilithmachines which use a pair of reciprocating vacuum lifters for feedingone sheet of paper at a time from the top of a paper stack into theprinting rolls. However, the invention will find utility in anypaper-using machine of a similar type, that is, one in which paper mustbe fed into the machine, one sheet at a time, by means of some type ofvacuum lifter system. Vacuum lifter feeds generally comprise a pair ofoverhead suction nozzles, which are mounted on a reciprocating paperfeed mechanism, and are connected by hoses to a suitable air evacuationpump. In almost all cases, the vacuum lifters are assisted by air liftmeans which supply a jet of air under the sheet of paper which is beinglifted by the vacuum lifter. Usually, a pair of such jets are located oneach side of the paper stack from which sheets are being fed, and arearranged to introduce a jet of air under the topmost sheet or sheetswhich rise in response to the action of the vacuum lifters.

A rising paper stack platform is almost universally used in associationwith vacuum lifter paper feed systems. The stack of paper supply issupported on a horizontal platform which rises a fraction of an incheach time a pre-determined number of paper sheets have been fed from thepaper stack on the platform.

The paper feed operation takes place at a location which may bedesignated as the upper leading edge of the paper stack. The termleading end of the paper stack refers to the end of the stack disposedin the direction in which the paper is fed from the stack into themachine. The term upper leading edge refers to the general location ofthe upper edge of the leading end of the paper stack. The paper stack isreplenished from the opposite or rear end. The previously mentioned airlift jets are applied to each side of the paper stack, just below itsupper surface,and just back of the upper leading edge of the stack.

In the typical vacuum paper feed system, the moveable vacuum liftersdescend and make vacuum seizure of the surface of the top sheet of paperan inch or two back of the upper leading edge; the top sheet is thenlifted and carried forward in the paper feed direction to the printingrolls.

It is very common for two or three or even more sheets of paper to sticktogether at the forward leading edge, so

3,403,903 Patented Oct. 1, 1968 that lifting the top sheet actuallylifts several sheets. The air jets at each side of the forward leadingedge are helpful in separating these sheets and forcing downward all butthe top sheet. However, it has generally been found necessary in all thecombination vacuum lifter and air lift paper feeds to provide paperseparator fingers of resilient spring material at the upper leading edgeof the paper stack. Usually, these separators are strips of springbronze, mounted in a small bracket, which is laterally adjustable at theleading face of the paper stack. The mounting brackets usually functionalso as leading end paper stops for seating the paper stack at itsleading end.

Unfortunately, the leaf-spring separators usually used in associationwith the vacuum lifter paper feed system have proven unreliable, unlessconstantly cared for by expert press operators. Consequently, mostmodern multilith machines employing this type of paper feed combinationare presently provided with some auxiliary device which may be called amultiple sheet detector. Usually, a pair of rolls on the paper sheetentering the printing section of the machine is supposed to detect thepresence of more than one paper sheet thickness, and automaticallyactuate a bypass of any such multiple sheet group which is improperlyentering the machine. These multiple sheet detectors naturally add tothe cost of the machine, and themselves present an operating andmaintenance problem. They do not function properly unless watched andserviced by an expert operator.

With the presently known leaf-spring fingers, no two of them everoperate exactly alike, and the same spring finger changes itscharacteristics each time it becomes slightly deformed in use, anoccurrence which is fairly common. Even when the leaf-spring finger isoperating at its best, its effectiveness as a paper separator is verymuch reduced if it deflects upwardly more than a few degrees. Suchdeflection resiliently deforms the leafspring, causing it to appear toshorten, and to turn its separating end upward rather than backward overand against the forward leading edges of the paper sheets which itshould be separating.

It is a major object of the present invention to provide an entirely newkind of sheet separator, and one which is so effective that no skill orattention is required from an unskilled operator. It is the purpose ofthe present invention, which has been achieved in actual application ofthe device to multilith machines, to achieve such effective separationby means of the sheet separator that no multiple sheet detector will beneeded in the machine.

It is an important associated object of the invention to provideseparators in which the separator finger is a rigid structure, whichrotates as a unit during separation, without any deformation, and whichis unchanging in structure and characteristics throughout its operatinglife.

Another important object is to provide a sheet separator in which thespring characteristic is substantially constant for the entire operatinglife of the separator, and the spring is entirely enclosed so that itcannot be damaged, or be deformed by rough and unskilled usage.

The foregoing and other objects of the invention are accomplished byusing an entirely enclosed torsion bar system for the resilient supportof rotatable but rigid separator fingers.

The foregoing and other objects and advantages of the invention may beunderstood from the following descrip- O tudinal vertical plane throughthe paper stack as indicated by the arrow 2 in FIG. 1;

FIG. 3 is a perspective view of an assembly comprising a paper stop forthe leading end of the paper stack, and a torsion bar separatorconstructed according to the invention;

FIG. 4 is an exploded perspective view of the assembly of FIG. 3, butviewed from the opposite side (the downstream side in terms of directionof paper movement);

FIG. 5 is an enlarged perspective view of the torsion bar separator,viewed from the downstream side, with the bearings shown incross-section in order to reveal the inner construction of the torsionbar spring system.

In FIG. 1, a paper stack 19 is seen (fragmentarially) supported on arising platform 11, which rises slowly during operation of the machine,by means well known to those familiar with multilith and similarmachines.

Overhead, a typical vacuum lifter system, indicated generally by thenumeral 12, reciprocates back and forth along a typical path suggestedby the double-ended arrow 13. The mechanically operated reciprocatingsystem is indicated only fragmentarially by the bar 14, since it istypical of such machines, and has no novel feature claimed as part ofthe present invention.

The bar 14 carries a typical pair of vacuum nozzles 15 and 16, fromwhich air is evacuated by a typical hose system indicated generally bythe numeral 17, and held on laterally adjustable brackets 18 and 19,respectively.

The typical air lift jets used in association with vacuum nozzles 15 and16 are designated by the numerals 21 and 22. Air under low pressureinside of the nozzles 21 and 22 is jetted from the small openingsindicated at 23, and cause the upper leading edges of the paper in paperstack 10 to be in a state of continuous vibration, which tends toproduce the desired separating operation. Nearby are side stops 24 and25 which assist the operator in properly locating the paper stack 10 forfeed along the desired center line into a multilith machine notillustrated.

The forward leading edge of the paper stack 10 is indicated by thenumeral 30. The paper stack 10 has its leading end seated against a pairof leading end paper stops 31 and 32, which are laterally adjustable ona horizontal, transverse support bar 33.

The vertical sectional view of FIG. 2 illustrates the operation of thepaper feed system, which includes the torsion bar separatordistinguishing the separator of the present invention from that of theprior art. The paper stack 10 is shown with its leading end 10a seatedagainst the vertical face of the paper stop 32.

In FIG. 1, the torsion bar separators of the invention are designated bythe numerals 41 and 42, respectively; and in FIG. 2, a side view of theseparator 42 shows that it is constructed of a stationary bracket 43,and a separator finger 44, having internal torsion bar construction tobe described hereinafter. The entire assembly 42 is integrally assembledinto the paper stop 32 by bolt 45.

In FIG. 2, the separator finger 44- is shown in rest position, but itsupwardly deflected position is indicated in dash-line at 46.

Although the paper stack 10 is raised a fraction of an inch at frequentintervals by automatic operation of the rising paper platform 11, theupper surface 10b of the paper stack 10 is normally a fraction of aninch below the elevation of separator finger 44. The combined action ofthe vacuum lifter 16 and air introduced underneath the top sheet 46, byboth atmospheric air pressure and air jetted from the air lifters 21 and22, causes the forward leading edge of sheet 46, and perhaps two orthree other sheets immediately beneath it, to rise against the undersideof the separator finger 44 as illustrated in FIG. 2.

However, as the lifter 16 moves away from a paper stack 10 in the paperfeed direction, the top sheet 47 is lifted to the position indicated indash-dot line by the numeral 48, and its forward leading edge deflectsthe finger 44 upward to the position 46. As this occurs, the resilientdownward pressure of finger 44 sweeps over the edges of any surplussheets, and with the assistance of air from the air lifters 21 and 22,the undesired sheets are forced downward.

It is important to note at this point that the action of spring finger44 is completely unlike that which has occurred with sheet separators ofthe prior art. The finger 44 of the present invention is a rigid plateof substantial construction, and is not deformed in the slightest. Evenwhen deflected upwardly to position 46, it presents a rigid scrapingaction to the edges of paper sheets. The brass spring fingers used onpresent paper separators are re siliently deformed by the paper action,and lose their efiicacy as paper separating fingers, during themomentary upward movement of top sheet 47 to position 48.

FIG. 2 also shows how the paper stop 42 may be slid into any desiredtransverse position on support bar 33, and clamped into that position bytightening the clamping screw 50.

FIGURFA 3 and 4 are perspective views of the leading end of paper stop32 and assembly and disassembly, respectively. It will be understoodthat the paper stop 31 is identical in construction. Ordinarily thepaper stops 31 and 32 are use-d in pairs, but in rare instances, narrowsheets might be fed utilizing only one stop, or very wide sheets mightrequire more than two such stops with their associated separators 41 and42.

It is seen that the paper stop 32 is comprised primarily of a paper stopplate structure 32a, to which the other parts are assembled aspreviously described. The bracket 43, which carries separator finger 44is seen to have a pair of tubular structures 51 and 52 in the upperportion. These are bearings seen in vertical, longitudinal cross-sectionin the enlarged perspective view of FIG. 5. Bearings 51 and 52 areaxially spaced from one another to accommodate separator finger 44between them.

FIG. 5 reveals that a tubular shaft 53 is rotatably mounted in bearings51 and 52, and entirely enclosed by them, except for a central portion53a, and a projectingin portion 53b. The rigid spring finger plate isintegrally attached to the torsion 53a, for example, by soldering.

A resilient torsion bar is co-axially disposed with bearings 51 and 52and tubular shaft 53, and entirely enclosed within their interiors. Atthe left end, as viewed in FIG. 5, the torsion bar 60 is anchored by astationary anchoring means 61 to the outboard end of the bearing 51. Atits right end, the torsion bar 60 rotates with the projecting end 53b ofthe tubular shaft 53, and is anchored to the interior thereof by arotating anchoring means 62, illustrated is dashed outline. It will beunderstood that anchoring means 61 and 62 are merely illustrative, butsome type of anchoring means are employed, but any suitable anchoringmeans may be used. For example, the tubes may be crimped and a drop ofsolder added to achieve anchoring.

It will be seen from the foregoing that the sheet separator of theinvention provides a resilient sheet separating action utterly unlikethat of the previously known leaf spring separators. Whereas the priorart separators were each unlike in characteristics, and oftenexperienced a change in characteristics as a result of deformationduring use, the sheet separator of the invention can be constructed toprecisely meet a desired spring characteristic, by proper selection oftorsion bar 60, and will retain its initial characteristic withoutvariation throughout its entire useful life.

It will be seen from the preferred embodiment illustrated that both theanchoring means 61 and 62 are preferably in an exposed position in whichthey can be inspected, repaired, or modified.

Also, it is a preferred modification of the invention to employ a springcharacteristic for torsion bar 60 which falls within the range ofstiffness determined by the properties of the paper in paper stack 10,and the operating characteristics of the vacuum lifter 16- and itsassociated air lifters 21 and 22.

While the embodiment illustrated is one of the best and most preferredforms of the invention, it is the intension of the inventor to includeall modifications and variations which fall within the scope of thefollowing claims.

What is claimed is:

1. In a vacuum paper feed system which includes means for presenting apaper stack for feed into a machine from an upper leading edge of saidstack, and a vacuum lifter means for lifting and passing into saidmachine one sheet of paper at a time, a sheet separator which includes:

a substantially vertical paper stop plate for seating against theforward side of said paper stack below said upper leading edge;

a pair of co-axial tubular bearing members mounted on said paper stopwith their axis parallel to and adjacent to the upper leading edge ofsaid paper stack, said bearing members being axially spaced from eachother;

a tubular shaft rotatably mounted in said members and having a centralportion exposed in the axial space between said bearing members;

a separator finger integral with said tubular shaft and projecting overthe leading edge of said paper stack, and adapted to engage the leadingedge of a sheet of paper raised from said stack by said vacuum liftermeans; i

a torsion bar co-axially disposed within said tubular shaft;

a rotating anchoring means for anchoring a first end 6 of said torsionbar to one end of said tubular shaft; and

stationary anchoring means for anchoring a second end of said torsionbar to the stationary structure comprising said paper stop and co-axialbearing members.

2. A'sheet separator as described in claim 1 in which the end of saidtubular shaft at which said rotating anchoring means is located projectsoutward of the open end of one of said tubular bearing means.

3. A sheet separator system as described in claim 1 in which two sheetseparator combinations are supported at the leading face of said paperstack, and are adjustably locatable along said upper leading edge ofsaid stack independently of each other to provide independent sheetseparator control at spaced intervals along said upper leading edge.

4. A sheet separator as described in claim 1 in which air lift meansassists said vacuum lifter by introducing a stream of air under theleading edge of paper lifted by said vacuum lifter and in which thespring characteristic of said torsion bar is strong enough to resistdeflection by a sheet of paper lifted by said air lift means, butyielding enough to be outwardly deflected by the leading edge of a sheetof paper lifted by a combination of said air lift and said vacuumlifter.

References Cited UNITED STATES PATENTS 1/1946 Curtis 27126 X EDWARD A.SROKA, Primary Examiner.

